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Publication numberUS4992115 A
Publication typeGrant
Application numberUS 07/310,569
Publication dateFeb 12, 1991
Filing dateFeb 15, 1989
Priority dateFeb 15, 1988
Fee statusLapsed
Also published asCA1333043C, DE68907112D1, DE68907112T2, EP0337075A2, EP0337075A3, EP0337075B1
Publication number07310569, 310569, US 4992115 A, US 4992115A, US-A-4992115, US4992115 A, US4992115A
InventorsSatoshi Ikeda
Original AssigneeNippon Paint Co., Ltd.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Surface treatment chemical and bath for aluminum and its alloy
US 4992115 A
Abstract
A surface treatment chemical for aluminum or its alloy comprising 10-1000 parts by weight of vanadium or cerium ion, 10-500 parts by weight of zirconium ion, 10-500 parts by weight of phosphate ion and 1-50 parts by weight of effective fluorine ion. A surface treatment bath for aluminum or its alloy comprising 10-1000 ppm of vanadium or cerium ion, 10-500 ppm of zirconium ion, 10-500 ppm of phosphate ion and 1-50 ppm of effective fluorine ion, and having pH of 2.0-4.0.
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Claims(10)
What is claimed is:
1. A surface treatment chemical for aluminum or an alloy of aluminum which consists essentially of 10-1000 parts by weight of vanadium or cerium ion, 10-500 parts by weight of zirconium ion, 10-500 parts by weight of phosphate ion and 1-50 parts by weight of effective fluorine ion; which surface treatment chemical is capable of being diluted to a pH of 2.0-4.0.
2. The surface treatment chemical according to claim 1, wherein said vanadium ion is 25-500 parts by weight, said zirconium ion is 20-100 parts by weight, said phosphate ion is 25-200 parts by weight, and said effective fluorine ion is 3-20 parts by weight.
3. The surface treatment chemical according to claim 1, wherein said cerium ion is 25-500 parts by weight, said zirconium ion is 20-500 parts by weight, said phosphate ion is 25-200 parts by weight, and said effective fluorine ion is 3-20 parts by weight.
4. A surface treatment bath for aluminum or its alloy consisting essentially 10-1000 ppm of vanadium or cerium ion, 10-500 ppm of zirconium ion, 10-500 ppm of phosphate ion and 1-50 ppm of effective fluorine ion, and having a pH of 2.0-4.0, which surface treatment bath is obtained by diluting the surface treatment chemical of claim 1 with water.
5. The surface treatment bath according to claim 4, wherein said vanadium ion is 25-500 ppm, said zirconium ion is 20-100 ppm, said phosphate ion is 25-200 ppm, and said effective fluorine ion is 3-20 ppm, and said bath has a pH of 2.7-3.3.
6. The surface treatment bath according to claim 4, wherein said cerium ion is 25-500 ppm, said zirconium ion is 20-500 ppm, said phosphate ion is 25-200 ppm, and said effective fluorine ion is 3-20 ppm, and said bath has pH of 2.7-3.3.
7. The surface treatment chemical according to claim 1 wherein said vanadium is present.
8. The surface treatment chemical according to claim 1 wherein said cerium is present.
9. The surface treatment bath according to claim 4 wherein said vanadium is present.
10. The surface treatment bath according to claim 4 wherein said cerium is present.
Description
BACKGROUND OF THE INVENTION

The present invention relates to a chemical or bath for surface-treating aluminum or its alloy, and more particularly to a surface treatment chemical or bath suitable for the surface treatment of aluminum cans for drinks.

Aluminum and its alloy are conventionally subjected to a chemical treatment to provide them with corrosion resistance and to form undercoating layers thereon. A typical example of such chemical treatment is a treatment with a solution containing chromic acid, phosphoric acid and hydrofluoric acid. This method can provide a coating having high resistance to blackening by boiling water and high adhesion to a polymer coating film formed thereon. However, since the solution contains chromium [VI], it is hazardous to health and also causes problems of waste water treatment. Thus, various surface treatment solutions containing no chromium [VI] have already been developed.

For instance, Japanese Patent Laid-Open No. 48-27935 discloses a method of treating aluminum or its alloy with a solution of pH of 3-5 which contains a water-soluble zinc salt, a water-soluble vanadate, a water-soluble fluoride or fluorine complex salt, an oxyacid salt of halogen as an oxidizing agent, etc. Japanese Patent Laid-Open No. 55-131176 discloses a method of surface-treating a metal [particularly aluminum] with a phosphate treating solution of pH 1.5-3.0 containing vanadate ion. Japanese Patent Publication No. 56-33468 discloses a coating solution for the surface treatment of aluminum, which contains zirconium, phosphate and an effective fluoride and has pH of 1.5-4.0. Further, Japanese Patent Laid-Open No. 56-136978 discloses a chemical treatment solution for aluminum or its alloy containing a vanadium compound, and a zirconium compound or a silicon fluoride compound.

However, in the method disclosed in Japanese Patent Laid-Open No. 48-27935, treating time is as long as 3-10 minutes, meaning poor efficiency, and the formed coating layer is turned gray, unsuitable for aluminum cans for drinks. Further, the conversion coating produced by this method does not have sufficient adhesion to a polymer coating film of paint, ink, lacquer, etc.

With respect to the method disclosed in Japanese Patent Laid-Open No. 55-131176, since it is a non-rinse method, it is not applicable to cans for drinks. In addition, the formed conversion coating tends to be blackened by treatment with boiled water for sterilization. Further, the coating layer does not have satisfactory adhesion to a painted coating layer.

With respect to the coating solution disclosed in Japanese Patent Publication No. 56-33468, it shows sufficient properties when it is a fresh solution, namely a newly prepared solution. However, after repeated use for chemical treatment, aluminum is accumulated in the solution by etching of the aluminum plates or sheets with fluorine. A conversion coating produced by such a coating solution does not show high resistance to blackening by boiling water and good adhesion to a polymer coating film. In addition, the formed conversion coating does not have good slidability, so cans treated with this solution cannot smoothly be conveyed.

Further, the treatment solution disclosed in Japanese Patent Laid-Open No. 56-136978 needs a treatment at a relatively high temperature for a long period of time, preferably at 50°-80° C. for 3-5 minutes, and the formed conversion coating does not have sufficient resistance to blackening by boiling water and sufficient adhesion to a polymer coating film. In addition, since the formed conversion coating is grayish, it cannot be suitably applied to aluminum cans for drinks.

OBJECT AND SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a surface treatment chemical for aluminum or its alloy free from the above problems inherent in the conventional techniques, which makes it possible to conduct a surface treatment at a low temperature in a short time to provide a conversion coating excellent in resistance to blackening by boiling water, adhesion to a polymer coating film formed thereon and slidability.

Another object of the present invention is to provide a surface treatment bath for aluminum or its alloy having such characteristics.

As a result of intense research in view of the above objects, the inventors have found that a combination of particular proportions of vanadium or cerium ion, zirconium ion, phosphate ion and effective fluorine ion can provide a surface treatment chemical and bath free from any problems of the conventional techniques. The present invention is based on this finding.

Thus, the surface treatment chemical for aluminum or its alloy according to the present invention comprises 10-1000 parts by weight of vanadium or cerium ion, 10-500 parts by weight of zirconium ion, 10-500 parts by weight of phosphate ion and 1-50 parts by weight of effective fluorine ion.

The surface treatment bath for aluminum or its alloy according to the present invention comprises 10-1000 ppm of vanadium or cerium ion, 10-500 ppm of zirconium ion, 10-500 ppm of phosphate ion and 1-50 ppm of effective fluorine ion, and has a pH of 2.0-4.0.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is perspective view showing a method of measuring the slidability of coated cans.

DETAILED DESCRIPTION OF THE INVENTION

The surface treatment chemical of the present invention contains a particular proportions of substances suitable for surface treatment of aluminum or its alloy, and it is diluted to a proper concentration as a surface treatment bath. Specifically, it contains 10-1000 parts by weight of vanadium or cerium ion [10-1000 ppm as a concentration in a surface treatment bath, same in the following]. When the content of the vanadium ion is less than 10 parts by weight [10 ppm], the formed conversion coating is turned black when treated with boiling water for sterilization, meaning that it is poor in resistance to blackening by boiling water. Further, it is poor in adhesion to a polymer coating film formed by painting, printing, etc. and in slidability. On the other hand, when the vanadium ion exceeds 1000 parts by weight [1000 ppm], further improvement due to the addition of vanadium ion cannot be obtained. Thus, from the economic point of view, 1000 parts by weight [1000 ppm] of vanadium ion is sufficient. The preferred content of vanadium ion is 25-500 parts by weight [25-500 ppm], and more preferably 25-200 parts by weight [25-200 ppm]. Sources of vanadium ion include vanadic acid and its salts such as HVO3, NH4 VO3, NaVO3, etc., vanadyl salts such as vanadyl sulfate, vanadyl oxalate, vanadium halides such as VF5, etc. Particularly, NH4 VO3 is preferable.

In the case of cerium ion, its content in the surface treatment chemical [surface treatment bath] is 10-1000 parts by weight [10-1000 ppm]. The reasons for limiting the content of cerium ion is essentially the same as those for vanadium ion. That is, when it is less than 10 parts by weight [10 ppm], the formed conversion coating is turned black when treated with boiling water for sterilization, meaning that it is poor in resistance to blackening by boiling water. Further, it is poor in adhesion to a polymer coating film and slidability. On the other hand, further improvement of resistance to blackening by boiling water and adhesion to a polymer coating film cannot be achieved by the addition of cerium ion in an amount exceeding 1000 parts by weight [1000 ppm]. Accordingly, from the economic point of view, up to 1000 parts by weight [1000 ppm] is sufficient. The content of cerium ion is preferably 25-500 parts by weight [25-500 ppm], and more preferably 25-200 parts by weight [25-200 ppm].

Sources of cerium ion include nitrates such as cerium [III] nitrate, ammonium cerium [IV] nitrate, etc., sulfates such as cerium [III] sulfate, cerium [IV] sulfate, etc., halides such as cerium [III] chloride, cerium [III] bromide, etc., and particularly cerium nitrates are preferable.

The surface treatment chemical [surface treatment bath] of the present invention further contains zirconium ion. The sources of zirconium ion include H2 ZrF6, [NH4 ]2 ZrF6, Na2 ZrF6, K2 ZrF6, Zr[NO3 ]4, ZrO[NO3 ]2, Zr[SO4 ]2, ZrOSO4, etc., and particularly [NH4 ]2 ZrF6 is preferable. The content of zirconium ion is 10-500 parts by weight [10-500 ppm]. When it is less than 10 parts by weight [10 ppm], a conversion coating-forming rate is extremely low, failing to produce a sufficient conversion coating. However, even though it exceeds 500 parts by weight [500 ppm], further effects cannot be obtained. Thus, from the economic point of view, it would be sufficient if it is up to 500 parts by weight [500 ppm]. In a case where vanadium ion is contained in the surface treatment chemical [surface treatment bath], the preferred content of zirconium ion is 20-100 parts by weight [20-100 ppm]. On the other hand, in a case where cerium ion is contained, the preferred content of zirconium ion is 20-500 parts by weight [20-500 ppm].

The surface treatment chemical [surface treatment bath] of the present invention further contains 10-500 parts by weight [10-500 ppm] of phosphate ion. When the content of phosphate ion is less than 10 parts by weight [10 ppm], the formed conversion coating has poor adhesion to a polymer coating film. On the other hand, when it exceeds 500 parts by weight [500 ppm], the formed conversion coating becomes poor in resistance to blackening by boiling water and adhesion to a polymer coating film, and further Zr.V.Al-PO4 tends to be precipitated in the surface treatment bath. The preferred content of phosphate ion is 25-200 parts by weight [25-200 ppm]. The sources of phosphate ion include H3 PO4, NaH2 PO4, [NH4 ]H2 PO4, etc., and particularly H3 PO4 is preferable.

The surface treatment chemical [surface treatment bath] of the present invention further contains 1-50 parts by weight [1-50 ppm] of effective fluorine ion. When the content of effective fluorine ion is less than 1 part by weight [1 ppm], substantially no etching reaction of aluminum takes place, failing to form a conversion coating. On the other hand, when it exceeds 50 parts by weight [50 ppm], the aluminum etching rate becomes higher than conversion coating-forming rate, deterring the formation of the conversion coating. In addition, even though a conversion coating is formed, it is poor in resistance to blackening by boiling water and adhesion to a polymer coating film. Incidentally, the term "effective fluorine ion" means isolated fluorine ion, and its concentration can be determined by measuring a treatment solution by a meter with a fluorine ion electrode. Thus, fluoride compounds from which fluorine ion is not isolated in the surface treatment solution cannot be regarded as the sources of effective fluorine ion. The sources of effective fluorine ion include HF, NH4 F, NH4 HF2, NaF, NaHF2, etc., and particularly HF is preferable.

The surface treatment bath is generally produced by diluting the surface treatment chemical to a proper concentration. The resulting surface treatment bath should have pH of 2.0-4.0. When the pH of the surface treatment bath is lower than 2.0, too much etching reaction of aluminum takes place, deterring the formation of the conversion coating. On the other hand, when it exceeds 4.0, Zr.V.Al-PO4 tends to be precipitated. The preferred pH of the surface treatment bath is 2.7-3.3.

The pH of the surface treatment bath may be controlled by pH-adjusting agents. The pH-adjusting agents are preferably nitric acid, sulfuric acid, etc. Phosphoric acid can serve as a pH-adjusting agent, but it should be noted that it cannot be added in an amount exceeding the above range because it acts to deteriorate the properties of the resulting conversion coating.

The surface treatment chemical [surface treatment bath] of the present invention may optionally contain organic chelating agent of aluminum such as gluconic acid [or its salt], heptonic acid [or its salt], etc.

The surface treatment chemical of the present invention may be prepared by adding the above components to water as an aqueous concentrated solution, and it may be diluted by a proper amount of water to a predetermined concentration with its pH adjusted, if necessary, to provide the surface treatment bath of the present invention.

The application of the surface treatment bath to aluminum or its alloy can be conducted by any methods such as an immersion method, a spraying method, a roll coat method, etc. The application is usually conducted between room temperature and 50° C., preferably at a temperature of 30°-40° C. The treatment time may vary depending upon the treatment method and the treatment temperature, but it is usually as short as 5-60 sec. Incidentally, aluminum or its alloy to which the surface treatment bath of the present invention is applicable includes aluminum, aluminum-copper alloy, aluminum-manganese alloy, aluminum-silicon alloy, aluminum-magnesium alloy, aluminum-magnesium-silicon alloy, aluminum-zinc alloy, alulminum-zinc-magnesium alloy, etc. It may be used in any shape such as a plate, a rod, a wire, a pipe, etc. Particularly, the surface treatment bath of the present invention is suitable for treating aluminum cans for soft drinks, alcoholic beverages, etc.

By treating aluminum or its alloy with the surface treatment bath of the present invention, the aluminum is etched with effective fluorine ion, and forms a double salt with vanadium or cerium ion, zirconium ion, phosphate ion and fluorine ion, thereby forming a conversion coating. It is presumed that zirconium serves as an accelerator of the precipitation of vanadium or cerium. As a result, vanadium or cerium exists in a relatively large proportion in the resulting conversion coating, and a surface layer of the conversion coating shows high corrosion resistance because of the corrosion resistance of vanadium or cerium. Thus, it is not blackened at all even after immersion in boiling water for 30 minutes. When the conversion coating is further printed or painted, the conversion coating shows extremely high adhesion to such a polymer coating film. This high adhesion seems to be derived from interaction of vanadium or cerium and the polymer coating film. Thus, by the interaction of vanadium or cerium ion, zirconium ion, phosphate ion and effective fluorine ion, a conversion coating with good corrosion resistance, high resistance to blackening by boiling water and slidability can be obtained.

The present invention will be explained in further detail by the following Examples and Comparative Examples. In the Examples and Comparative Examples, resistance to blackening by boiling water, adhesion to a polymer coating film and slidability are evaluated as follows:

[1] Resistance to blackening by boiling water

Each aluminum can treated with a surface treatment bath is dried, and a bottom portion is cut off from the can, and then immersed in boiling water at 100° C. for 30 minutes. After that, the degree is evaluated as follows:

: Not blackened at all.

: Extremely slightly blackened.

Δ: Slightly blackened.

X: Considerably blackened.

XX: Completely blackened.

[2] Adhesion to polymer coating film

Each aluminum can treated with a surface treatment bath is dried, and its outer surface is further coated with epoxy-phenol paint [Finishes A, manufactured by Toyo Ink Manufacturing Co., Ltd.] and then baked. A polyamide film of 40 μm in thickness [Diamide Film #7000 manufactured by Daicel Chemical Industries, Ltd.] is interposed between two of the resulting coated plates and subjected to hot pressing. A 5-mm wide test piece is cut off from the hot pressed plates, and to evaluate the adhesion of each test piece, its peel strength is measured by a T-peel method and a 180° peel method. The unit of the peel strength is kgf/5 mm. Incidentally, the adhesion measured on a test piece before immersion in boiling water is called "primary adhesion," and the adhesion measured on a test piece after immersion in running water at 90° C. for 7.5 hours is called "secondary adhesion."

[3] Slidability

As shown in FIG. 1, two surface-treated aluminum cans 2, 2' are fixed to a sliding plate 1 whose inclination angle θ can be changed, with a double-sided adhesive tape in such a manner that bottoms 3, 3' of the aluminum cans 2, 2' face downward. Two additional surface-treated aluminum cans 4, 4' are placed on the aluminum cans 2, 2' perpendicularly in such a manner that each bottom 5, 5' of the cans 4, 4' faces oppositely, and that lines by rolling is directed vertically. Further, the two cans 4, 4' are fixed to each other with a double-sided adhesive tape in side portions not in contact with the lower cans 2, 2'.

By raising the sliding plate 1 to increase its inclination angle θ, an angle θ at which the upper two cans 4, 4' start to slide is measured. A friction constant is calculated from tan θ. The friction coefficient is evaluated as follows:

: less than 0.7

: 0.7 or more and less than 0.8

Δ: 0.8 or more and less than 0.9

X: 0.9 or more and less than 1.0

XX: 1.0 or more

EXAMPLES 1-10, COMPARATIVE EXAMPLES 1-8

An aluminum sheet [JIS-A-3004] is formed into a can by a Drawing & Ironing method, and degreased by spraying an acidic cleaner [Ridoline NHC 100 manufactured by Nippon Paint Co., Ltd.]. After washing with water, it is sprayed with a surface treatment bath having the composition and pH shown in Table 1 at 40° C. for 30 sec. Next, it is washed with water and then with deionized water, and then dried in an oven at 200° C. After drying, each can is tested with respect to resistance to blackening by boiling water, adhesion to a polymer coating film and slidability. The results are shown in Table 2.

              TABLE 1______________________________________                             EffectiveVanadium   Zirconium Phosphate                             FluorineIon.sup. (1)           Ion.sup. (2)                     Ion.sup. (3)                             Ion.sup. (4)No.  (ppm)      (ppm)     (ppm)   (ppm)   pH.sup.(5)______________________________________Example 1   50         45        70      8       3.0 2   25         45        70      8       3.0 3   50         20        70      8       3.0 4   50         45        25      8       3.0 5   50         45        200     8       3.0 6   50         45        70      3       3.0 7   50         45        70      20      3.0 8   50         45        70      8       2.7 9   50         45        70      8       3.310   25         20        25      8       3.0Comparative Example 1    5         45        70      8       3.0 2   50          5        70      8       3.0 3   50         45         5      8       3.0 4.sup.(6)50         45        70        0.3   3.0 5   50         45        70      8       1.8 6.sup.(6)50         45        70      8       4.2 7    0         45        70      8       3.0 8   50          0        70      8       3.0______________________________________ Note  .sup.(1) Added as NH4 VO3. .sup.(2) Added as (NH4)2 ZrF6. .sup.(3) Added as H3 PO4. .sup.(4) Added as HF. .sup.(5) Controlled with HNO3 and an ammonium aqueous solution. .sup.(6) Turned cloudy.

              TABLE 2______________________________________Adhesion of Coating FilmResistance to        T-Peel     180°-PeelBlackening by        Method     MethodNo.  Boiling Water            Prim.   Sec. Prim. Sec. Slidability______________________________________Example 1   ⊚            5.3     2.5  4.3   2.9  Δ 2   ○    4.9     2.4  4.5   3.0  ○ 3   ⊚            4.3     2.0  4.2   2.8  ○ 4   ⊚            4.4     2.1  4.1   2.6  ○ 5   ○    4.2     2.1  4.2   2.6  Δ 6   ⊚            4.8     2.3  4.4   2.8  ○ 7   ⊚            4.8     2.4  4.4   3.0  ○ 8   ⊚            5.0     2.3  4.4   3.1  ○ 9   ⊚            5.1     2.3  4.3   3.0  ○10   ⊚            5.1     2.4  4.2   3.0  ○Comparative Example 1   .sup.  X    2.2     0.7  2.5   1.6  X 2   XX          0.7     0.3  2.0   0.8  X 3   .sup.  X    2.0     0.6  2.3   1.6  Δ 4   XX          0.6     0.3  2.1   0.6  X 5   Δ     2.1     0.6  2.3   1.5  Δ 6   Δ     1.9     0.5  2.0   0.9  Δ 7   .sup.  X    2.0     0.7  2.4   1.6  X 8   XX          0.6     0.3  1.8   0.8  Δ______________________________________

As is clear from the above results, in the case of treatment with the surface treatment bath of the present invention [Examples 1-10], the formed conversion coatings are good in resistance to blackening by boiling water, adhesion to a polymer coating film and slidability. On the other hand, when the vanadium ion is less than 10 ppm [10 parts by weight] [Comparative Examples 1 and 7], the formed conversion coatings are poor in resistance to blackening by boiling water, adhesion to a polymer coating film and slidability. And when zirconium is less than 10 ppm [10 parts by weight] [Comparative Examples 2 and 8], and when effective fluorine ion is less than 1 ppm [1 parts by weight] [Comparative Example 4], sufficient conversion coatings are not formed, and they are poor in resistance to blackening by boiling water, adhesion to a polymer coating film and slidability. Incidentally, in Comparative Example 4, the treating bath becomes cloudy by precipitation. Further, when phosphate ion is less than 10 ppm [10 parts by weight] [Comparative Example 3], the resulting conversion coating is poor in resistance to blackening by boiling water and adhesion to a polymer coating film. When the pH of the surface treatment bath is less than 2.0 [Comparative Example 5], a conversion coating is not easily formed, and the formed conversion coating is slightly blackened and shows poor adhesion to a polymer coating film. On the other hand, when the pH exceeds 4.0 [Comparative Example 6], the treating bath becomes cloudy because of precipitation, and the resulting conversion coating is slightly poor in resistance to blackening by boiling water and also shows poor adhesion to a polymer coating film.

EXAMPLES 11-20, COMPARATIVE EXAMPLES 9-16

The surface treatment of aluminum sheets is conducted in the same manner as in Examples 1-10 and Comparative Examples 1-8 except for using surface treatment baths having the compositions and pH shown in Table 3, and resistance to blackening by boiling water, adhesion to a polymer coating film and slidability are tested on the resulting conversion coatings. The results are shown in Table 4.

              TABLE 3______________________________________                             EffectiveCerium     Zirconium Phosphate                             FluorineIon .sup.(1)           Ion .sup.(2)                     Ion .sup.(3)                             Ion .sup.(4)No.  (ppm)      (ppm)     (ppm)   (ppm)   pH.sup.(5)______________________________________Example11   50         50        50      8       3.012   25         50        50      8       3.013   50         25        50      8       3.014   50         50        25      8       3.015   50         50        200     8       3.016   50         50        50      3       3.017   50         50        50      20      3.018   50         50        50      8       2.719   50         50        50      8       3.320   25         25        25      8       3.0Comparative Example 9    5         50        50      8       3.010   50          5        50      8       3.011   50         50         5      8       3.012   50         50        50        0.3   3.013   50         50        50      8       1.814   50         50        50      3       4.215    0         50        50      20      3.016   50          0        50      8       3.0______________________________________ Note .sup.(1) Added as Ce(NH4)2 (NO3)6. .sup.(2) Added as (NH4)2 ZrF6. .sup.(3) Added as H3 PO4. .sup.(4) Added as HF. .sup.(5) Controlled with HNO3 and an ammonium aqueous solution.

              TABLE 4______________________________________Adhesion of Coating FilmResistance to        T-Peel     180°-PeelBlackening by        Method     MethodNo.  Boiling Water            Prim.   Sec. Prim. Sec. Slidability______________________________________Example11   ⊚            4.7     2.2  4.0   2.7  Δ12   ○    4.6     2.3  4.1   2.8  ○13   ⊚            4.1     2.0  4.0   2.6  ○14   ⊚            4.5     2.1  3.9   2.4  ○15   ○    4.0     2.2  3.9   2.5  ○16   ⊚            4.4     2.3  4.3   2.6  ○17   ⊚            4.2     2.3  4.2   2.7  ○18   ⊚            4.7     2.2  4.2   3.0  ○19   ⊚            4.6     2.4  4.1   2.8  ○20   ⊚            4.4     2.2  4.0   2.7  ○Comparative Example 9   .sup.  X    2.2     0.7  2.5   1.6  X10   XX          0.7     0.3  2.0   0.8  X11   .sup.  X    2.0     0.5  2.3   1.5  Δ12   XX          0.7     0.3  2.2   0.7  X13   Δ     2.2     0.6  2.2   1.6  Δ14   Δ     1.9     0.6  2.0   0.8  Δ15   .sup.  X    2.0     0.7  2.4   1.6  X16   XX          0.6     0.3  1.8   0.9  X______________________________________

As is clear from the above results, in the case of treatment with the surface treatment bath of the present invention [Examples 11-20], the formed conversion coatings are good in resistance to blackening by boiling water, adhesion to a polymer coating film and slidability. On the other hand, when the cerium ion is less than 10 ppm [10 parts by weight] [Comparative Examples 9 and 15], the formed conversion coatings are poor in resistance to blackening by boiling water, adhesion to a polymer coating film and slidability. And when zirconium is less than 10 ppm [10 parts by weight] [Comparative Examples 10 and 16], and when effective fluorine ion is less than 1 ppm [1 parts by weight] [Comparative Example 12], sufficient conversion coatings are not formed, and they are poor in resistance to blackening by boiling water, adhesion to a polymer coating film and slidability. Incidentally, in Comparative Example 12, the treating bath becomes cloudy by precipitation. Further, when phosphate ion is less than 10 ppm [10 parts by weight] [Comparative Example 11], the resulting conversion coating is poor in resistance to blackening by boiling water and adhesion to a polymer coating film. When the pH of the surface treatment bath is less than 2.0 [Comparative Example 13], a conversion coating is not easily formed, and the formed conversion coating is slightly blackened and shows poor adhesion to a polymer coating film. On the other hand, when the pH exceeds 4.0 [Comparative Example 14], the treating bath becomes cloudy because of precipitation, and the resulting conversion coating is slightly poor in resistance to blackening by boiling water and also shows poor adhesion to a polymer coating film.

As described above in detail, with the surface treatment chemical [surface treatment bath] of the present invention, a conversion coating having extremely high corrosion resistance can be formed on a surface of aluminum or its alloy in a very short time. The conversion coating thus formed is highly resistant to blackening even when immersed in boiling water, meaning that it has excellent resistance to blackening by boiling water even in a thin layer. In addition, when an upper polymer coating film is formed on the conversion coating by painting or printing, extremely strong bonding between them can be achieved. Further, since the conversion coating shows good slidability, it is extremely advantageous in conveying.

Since the surface treatment chemical [surface treatment bath] of the present invention shows sufficient characteristics even though its concentration is varied, it is not required to strictly control the concentration of the surface treatment bath.

The surface treatment chemical [surface treatment bath] having such advantages are highly suitable for surface treatment of aluminum cans, etc.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4148670 *Dec 30, 1976Apr 10, 1979Amchem Products, Inc.Containing phosphates, fluorides, and zirconium or titanium compound
US4264378 *Feb 14, 1980Apr 28, 1981Oxy Metal Industries CorporationChromium-free surface treatment
US4470853 *Oct 3, 1983Sep 11, 1984Coral Chemical CompanyCoating compositions and method for the treatment of metal surfaces
DE3236247A1 *Sep 30, 1982Apr 12, 1984Metallgesellschaft AgVerfahren zur oberflaechenbehandlung von aluminium
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5192374 *Sep 27, 1991Mar 9, 1993Hughes Aircraft CompanyBoehmite with cerium oxide or cerium hydroxide
US5194138 *Jul 20, 1990Mar 16, 1993The University Of Southern CaliforniaTreatment with cerium nitrate and cerium chloride, positively charging in presence of molybdate anions
US5421913 *Dec 23, 1993Jun 6, 1995Nippon Paint Co., Ltd.Surface treatment chemicals and bath for aluminum or its alloy and surface treatment method
US5531931 *Dec 30, 1994Jul 2, 1996Cargill, IncorporatedGluconate, ascorbate, tartrate, or saccharate salts mixed with rare earth metal salts
US5582654 *May 20, 1994Dec 10, 1996The University Of Southern CaliforniaDeoxidizing, immersing the surface in cerium nitrate solution, electrically charging while contacting with sodium molybdate solution, finally immersing in cerium chloride solution
US5603754 *Jul 5, 1994Feb 18, 1997Henkel CorporationAqueous liquid composition for protective coating containing dissolved titanium or zirconium compound, oxidizing agent, fluoride compound, phosphate compound
US5954893 *Nov 13, 1995Sep 21, 1999The Secretary Of State For DefenceAnodizing substrate to form porous surface layer, applying a metavanadate solution or gel, separately applying a solution containing a metal cation which coprecipitates with the metavanadate within the surface pores
US6027579 *Jul 7, 1997Feb 22, 2000Coral Chemical CompanyRinse comprising zirconium ions, vanadium ions, fluoride ions, and phosphate ions in a ratio and a concentration effective for providing the phosphate conversion-coated ferrous metal substrate with improved corrosion resistance
US6040280 *Nov 27, 1996Mar 21, 2000Henkel CorporationA liquid concentrate for mixing with water to coat aluminum cans, reducing coefficient of static friction on their exterior walls then decorated by labeling, printing
US6190780 *Jun 8, 1998Feb 20, 2001Nippon Steel CorporationSurface treated metal material having a corrosion resistant coating layer consisting essentially of an oxyacid compound or hydrogen oxyacid compound of a rare earth element or group iva element, or a mixture thereof, on the surface of a metal
US6248184 *May 11, 1998Jun 19, 2001The Boeing CompanySealing solution consisting of a dilute solution of cerium and yttrium salts; nontoxic; paint adhesion; corosion resistance; aerospace
US7175882 *Oct 1, 2001Feb 13, 2007Henkel Kommanditgesellschaft Auf AktienCorrosion resistant protective coatings; heat conductivity
US7402214 *Apr 28, 2003Jul 22, 2008Ppg Industries Ohio, Inc.Conversion coatings including alkaline earth metal fluoride complexes
US7507480May 31, 2005Mar 24, 2009Brookhaven Science Associates, LlcUltrathin film of a combination of crosslinked amido-functionalized silanol component and rare earth oxide nanoparticles, formed by reaction of an amino-functional silanetriol and a rare earth carboxylate, whereby the freed carboxylic acid amidates the siloxane; less than ten nanometers thick
US7815751 *Sep 28, 2005Oct 19, 2010Coral Chemical CompanyZirconium-vanadium conversion coating compositions for ferrous metals and a method for providing conversion coatings
US8097093Sep 25, 2008Jan 17, 2012Ppg Industries Ohio, IncMethods for treating a ferrous metal substrate
US8652270Dec 7, 2011Feb 18, 2014Ppg Industries Ohio, Inc.Methods for treating a ferrous metal substrate
US20110041958 *Oct 27, 2010Feb 24, 2011Nihon Hyomen Kagaku Kabushiki KaishaChromium-free solution for treating metal surfaces
US20110120873 *Jan 7, 2009May 26, 2011Airbus Operations GmbhMultifunctional coating of aluminium pieces
CN100552086CMar 15, 2007Oct 21, 2009西安建筑科技大学Normal temperature fast filming fluid for aluminium alloy surface and its usage
WO1995002077A1 *Jul 5, 1994Jan 19, 1995Tomoyuki AokiComposition and process for treating tinplate and aluminum
WO2001086016A2 *May 11, 2001Nov 15, 2001Henkel CorpMetal surface treatment agent
WO2002028549A1 *Oct 1, 2001Apr 11, 2002Lawrence R CarlsonProcess for coating metal surfaces
WO2002028550A1 *Oct 1, 2001Apr 11, 2002Shawn E DolanProcess for imparting corrosion resistance
WO2009132369A2 *Apr 28, 2009Nov 5, 2009Echem Komptenzzentrum Für Angewandte Elektrochemie GmbhClutch
Classifications
U.S. Classification148/247, 148/261
International ClassificationC23C22/44, C23C22/36
Cooperative ClassificationC23C22/361, C23C22/44
European ClassificationC23C22/44, C23C22/36A
Legal Events
DateCodeEventDescription
Apr 8, 2003FPExpired due to failure to pay maintenance fee
Effective date: 20030212
Feb 12, 2003LAPSLapse for failure to pay maintenance fees
Aug 28, 2002REMIMaintenance fee reminder mailed
Aug 4, 1998FPAYFee payment
Year of fee payment: 8
Jul 25, 1994FPAYFee payment
Year of fee payment: 4
Feb 15, 1989ASAssignment
Owner name: NIPPON PAINT CO., LTD., JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:IKEDA, SATOSHI;REEL/FRAME:005042/0887
Effective date: 19890125